1. Field of the Invention
The present invention relates to semiconductor devices and semiconductor chips, and particularly, to a semiconductor device or a semiconductor chip having an operation securing circuit for controlling the temperature of hard macro cores contained in the semiconductor device or chip and securing a wide operating temperature range for the semiconductor device or chip.
2. Description of the Related Art
Digital consumer products such as digital cameras have a variety of functions such as image and voice processing functions, and therefore, they must have processing capacity comparable to personal computers. In addition, the digital consumer products are required to be compact, portable, low power consumption, and manufacturable at low cost. To meet these requirements, there are techniques to arrange integrated circuits having different functions on a single semiconductor chip to provide a one-chip system LSI. Such an LSI satisfies a variety of requirements and provides improved processing capacity.
The one-chip system LSI consists of different hard macro cores or functional blocks including microprocessors, digital signal processors, flash memories, static RAMS, and dynamic RAMS. To make the designing of system LSIs easier, a library is prepared to store data such as delay times and operating temperature ranges related to hard macro cores. Data about necessary hard macro cores is picked up from the library when designing a required system LSI.
The hard macro cores consist each of cells and have different operating temperature ranges. Accordingly, a system LSI consisting of different hard macro cores is designed to have an operating temperature range that is of a hard macro core having a narrowest operating temperature range. Namely, the lowest operating temperature of a system LSI is equal to a highest lower limit among the operating temperature ranges of hard macro cores contained in the system LSI. Similarly, the highest operating temperature of the system LSI is determined by a lowest higher limit among the operating temperature ranges of the hard macro cores. For example, a system LSI consisting of a hard macro core A having an operating temperature range of -10.degree. C. to 80.degree. C. and a hard macro core B having an operating temperature range of -40.degree. C. to 60.degree. C. assures an operating temperature range of -10.degree. C. to 60.degree. C. It is difficult for this system LSI to expand the operating temperature range while maintaining the operating temperature range of each hard macro core contained in the system LSI.
The operating temperature ranges of hard macro cores are usually dependent on periods they were developed, or on customers' requests. If a system LSI is made of a mixture of hard macro cores having different operating temperature ranges, the operating temperature range of the system LSI is restricted by the hard macro core that has the narrowest operating temperature range. To expand the operating temperature range of such a system LSI, the operating speed thereof must be sacrificed.